There has recently been renewed and increased interest in the dopaminergic activity of apomorphine. Of particular note are reports that apomorphine has some effectiveness in treating Parkinsonism. Despite interest in the pharmacological activity and therapeutic use of apomorphine, relatively little is known about the mammalian metabolism of this drug. Since the metabolism of a drug may often affect its biological potency and spectrum of activity, a systematic study of the metabolism of apomorphine in four mammalian species is proposed. Comparative metabolic profiles may yield some indication of the metabolism of apomorphine in man. Also proposed is a study of the metabolic fate of six analogs of apomorphine. These compounds are apomorphine pro-drugs; that is, they can potentially be converted to apomorphine in vivo. Metabolic studies with these apomorphine congeners should permit evaluation of the potential therapeutic usefulness of such compounds. In order to complete the proposed investigations, analytical methods will be required that are specific and highly sensitive towards apomorphine, its congeners, and metabolites. Gas chromatographic procedures and a novel radiochemical procedure seem most promising. Application of the developed procedures to spiked human urine will be attempted as a prelude to possible future human metabolism studies. The proposed studies should lead to a greater understanding of aporphine metabolism in general. Thus, these investigations assume greater fundamental importance because of the wide occurrence of aporphines in the plant kingdom and their purported use as drugs.